Urinary System 3 Flashcards
What are the relations of the bladder in the male?
Anterior:
* pubic symphysis
Posterior:
* rectum
* ductus deferens
* seminal vesicles
Superior:
* peritoneum
* intestines
Inferior:
* prostate gland
What are the relations of the bladder in the female?
Anterior:
* pubic symphysis
Posterior:
* vagina
Superior:
* uterus
Inferior & lateral:
* muscles of the pelvic floor & sidewall
What are some details about ureters?
- Tubes carry urine from
each kidney to bladder - 25–30 cm long & ~3-4 mm
in diameter - Pass urine by peristaltic
waves (smooth muscle) - Enter the back of bladder
- Urine backflow - prevented
by ureterovesical valves
What is the structure of the bladder?
- Hollow smooth muscle organ
- Bladder can be divided into two
parts:
1) Body (lying above ureteral
orifices)
2) Base (Consisting of trigone
and bladder neck - Its muscular wall is formed of
smooth muscle cells (detrusor)
Anatomy of the urinary bladder: know the labels
whiteboard.
What are some facts about the urinary bladder?
- The only involuntary organ in the body under voluntary control
- All humans are incontinent at birth
- Activation of numerous neurologic reflexes are learned in
early life to control the bladder - 35+ reflexes coordinate activities of bladder smooth muscle,
plus striated & smooth muscle of the urethra
What happens in bladder filling + voiding?
Filling:
*the detrusor is relaxed
*the bladder neck is closed
Voiding:
*the detrusor contracts
*the bladder neck opens
Describe what controls the micturition reflex of the urinary bladder and higher control of it
- Activated when urinary bladder
stretched
– Results in micturition
Control of the Micturition Reflex by
Higher Brain centres requires
coordination:
1. Central nervous system
2. Spinal cord ( integrated sacral region)
3. Autonomic nervous system (pelvic &
hypogastric nerves)
4. Somatic nervous system (mainly pudendal
nerve)
What are the 2 phases of the micturition reflex of the bladder?
*voiding phase
*storage phase
What happens in the storage phase?
*As the Bladder fills
pressure stays low pressure stays low due to a highly elastic nature
*Manifestation of Laplace Law:
Pressure =Pressure = 2 x wall tension2 x wall tension
in sphere radiusin sphere radius
(i.e. pressure increases but so does radius)
*i) Bladder full - pressure is detected
ii) Messages sent to brain
Voluntary & local reflexes cause a switch to Voiding phase
What happens in the voiding phase?
i) Voluntary signals relax
external sphincterexternal sphincter (somatic)(somatic)
ii) Autonomic contractionii) Autonomic contraction
of detrusor muscleof detrusor muscle
Urethra - excitatory role
which maintains flow till
bladder is empty
What is the micturition reflex + all about this?
- Activated by stretch of urinary bladder
(trigone) - Eventually Action potentials travel along
sensory nerves in pelvic nerve to sacral
region of spinal cord - Integrated at spine - AP travel Along
parasympathetic nerve to urinary
bladder
– Bladder contracts - External sphincter normally contracted
as result of somatic motor nervous
system
– Decreased AP cause Urethral sphincter to
relax
all about activation of the micturition reflex
- Normally Activated by stretch of urinary
bladder (trigone) - Can also be activated by irritation from
bacterial infections – in urinary bladder
– Desire to void
– Occurs when bacteria pass up along urethra
and enter and multiply within the bladder,
causing inflammation
– Usually caused by bacteria from the GI tract,
eg E.coli
– WBC and RBC in urine
Summary of sympathetic NS, parasympathetic NS and somatic NS
- Sympathetic NS (“Continence”):
– Relaxes Detrusor muscle & Constricts Internal sphincter - Parasympathetic NS:
– Contracts detrusor muscle & Relaxes internal sphincter - Somatic NS:
– Voluntary constriction of external sphincter to prevent micturition
